Understanding Rivet Sizing
Selecting the correct rivet size is critical for creating strong, reliable joints in sheet metal, structural assemblies, and fabrication projects. The two primary dimensions are rivet diameter and grip length. The diameter determines shear and tensile strength, while the grip length must match the total thickness of the materials being joined.
The general rule is that rivet diameter should be at least 3 times the thickness of the thickest sheet being joined. The grip range should cover the total material thickness with some allowance for the rivet to properly form the shop head (bucked end) or mandrel break.
Rivet Sizing Formulas
Standard Blind Rivet Sizes
| Rivet Dash No. | Diameter (in) | Hole Size (in) | Grip Range (in) | Shear (lbs) - Aluminum |
|---|---|---|---|---|
| 3-2 | 3/32 (0.094) | 0.098 | 0.032-0.125 | 110 |
| 4-2 | 1/8 (0.125) | 0.129 | 0.032-0.125 | 200 |
| 5-4 | 5/32 (0.156) | 0.160 | 0.126-0.250 | 310 |
| 6-6 | 3/16 (0.188) | 0.192 | 0.251-0.375 | 450 |
| 8-8 | 1/4 (0.250) | 0.257 | 0.376-0.500 | 700 |
Rivet Type Selection Guide
- Blind (Pop) Rivets: Installed from one side only. Ideal when access to the back of the joint is limited. Available in aluminum, steel, and stainless steel.
- Solid Rivets: Strongest type. Requires access to both sides for bucking. Used in aircraft structures and heavy structural work.
- Semi-Tubular Rivets: Easier to set than solid rivets but nearly as strong. Commonly used in electronics, hardware, and light structural applications.
- Drive Rivets: A short mandrel is driven into the rivet body to expand it. Used for nameplates, hinges, and non-structural applications.
Frequently Asked Questions
How do I choose between aluminum and steel rivets?
Use aluminum rivets for aluminum-to-aluminum joints and lightweight applications where corrosion resistance is needed. Use steel rivets when higher shear and tensile strength is required or when joining steel components. For mixed-metal joints, use stainless steel rivets to minimize galvanic corrosion.
What happens if the grip length is too long or too short?
A grip length that is too short will not properly clamp the materials, resulting in a loose, weak joint. A grip length that is too long wastes material and may not form a proper shop head. For blind rivets, the mandrel may not break correctly if the grip range is wrong.
Can I use a rivet in a load-bearing application?
Yes, rivets are used in many structural and load-bearing applications including aircraft, bridges, and building frames. However, you must calculate the shear and tensile loads and select a rivet diameter and material that provides adequate strength with an appropriate safety factor (typically 3:1 to 5:1).